86GT AOD Overheating issue my Btu Saga!! Solved.

1. Thermostat in backwards from PO replaced with 195F unit and flushed system. $15. Some benefit but no cigar.

2. Replaced the fan clutch = $36 no noticable difference but needed one as due to dirt stuck on face from leaking silicon = was original.

3. Replaced temperature sending unit $6.50 made it worse slightly. Crap.

4. Installed temperature reading radiator cap $25 showed temp at 170F with 195F thermostat. No problem is indicated in reality. Nice invention.

5. Replaced plug in Ford resister behind gas gage on instrument panel $36 from Amazon.com. Reading is dead normal.

6. When the fan is set on high no matter if AC is on or not the temp gage goes up 1/8" but temp on radiator cap stays 170F. Due to high amps on that speed only.

http://picasaweb.google.com/twistedwankel/86OverheatingSolutions#

7. Will be putting in new 3 row radiator from CJPony next week. Will post pix if anything is interesting or not tempwise?!

8. No matter what my "overheating" issues are definately resolved with the stock radiator no less!! If the new radiator wasn't so cool and cheap I could send it back. But it will out live me.

9. Installed new 3 row radiator from CJPony. $126= Perfect fit and great construction. Car runs at 5/8 gage when hot with AC on. Not pleased with gage reading yet but radiator thermostat indicates no issue overheating at all.

10. Cleaned original temp gage sending unit and replaced the new unit with the old one. IMMEDIATELY reading is below normal straight up when hot 180F on radiator cap thermostat. Only moves up 1/8" to straight up normal on high fan setting. Otherwise sits below straight up See pix.

11. Ran car for an hour at idle with AC on max with full fan on and it never budged off Normal straight up. Any other fan speed or off and it fell below straight up at 180F on radiator cap gage

Definately a homerun this time!! Apparently no matter how big a radiator you install it will eventually reach a "happy" temp and never deviate from that no matter how hot it gets. Mine won't budge off 180F with or without the AC running. I will take car autocrossing Saturday and give it the "final evaluation" with alot of heat coming off the AOD. But expect zero surprises.

12.AUTOCROSSING = Over 90F outside temp with hot concrete pavement had to be 100F according to my feet and hot tires.

Airport Autocross 1st and 2nd gear only AOD (PIA to get 2nd gear twice).

Four approx One Minute Runs about 5 minutes apart. Let engine run for two minutes to cool down AOD according to in car factory gage and then shut it off for 3 minutes.

Never got over normal (straight up) on gage which read 185F max on the radiator cap dial thermometer. But would fall back to 180F after cool down and interior temp gage would quickly fall back down to under 1/2 scale

Mind you this is using a 195F thermostat so I'm thinking a 180F unit might keep things cooler still? BUT the other sending unit for the Fuel Injection wants to see 195F and I don't want the car running rich either.

This concludes my cooling system restoration on the cheap.

NikwoaC said:

I don't know how much I trust those radiator cap thermometers. If you think about it, the water that the radiator cap is exposed to has run out of the engine and across the radiator before it even gets there, so the reading of that temp is going to be (at least somewhat) lower than the coolant in the engine.

Regardless, good to hear you've got it figured out!

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Considering Radiator Cap Thermometers were the "original" technology for cars AND it reads perfect ambient temp of 90F before I used it it's good enough for a baseline. Better than the meat thermometer I tried using before @ the hose fitting. Keeping in mind that it sits at the top of the all metal radiator just above the AOD cooling tank it is probably hotter than the fluid leaving out the bottom hose and re-entering the engine. So I would say it's arguably a worse case scenario?

We can assume that the water entering the top hose of the radiator meets or exceeds 195F too And the goal of the thermostat/radiator is to keep the whole motor about a constant 195F. I also found it interesting that the overflow tank only goes up 1/2" now at the extreme temps of racing but doesn't budge during normal driving.

I will put the old ugly radiator cap back on now that I know the factory gage is working properly. The "purdy one" is just for testing all my cars now.

HISSIN50 said:

Did you ever tryin interpolating the ECT reading to see what temps it was reading?

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Would need baby Jesus to come visit me in my dreams to do that? I assume there must be a dc voltage involved somewhere in this interpolation? I ran a search on ECT just now and got nothing!!

HISSIN50 said:

This might help:

Ford Fuel Injection Engine Coolant Temperature Sensor (ECT)

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Thanks. That is really cool. AND very useful. Which begs the question...Why didn't Ford use the ECT for the stupid temp gage too? Appears to be way more accurate.